In modern society, numerous documents and cards with forgery and duplication being prohibited are in circulation, such as bank notes, checks, securities, and cards. The forgery and duplication of these items must not only be prohibited by law, but must also be rendered technically impossible to maintain social order. However, copying and duplication technologies have made alarming strides in recent years, with the risk of forgery and duplication increasing each year. The crime of forgery has been increasing of late, and the techniques employed are becoming ever more sophisticated.
Accordingly, various techniques of preventing forgery and duplication have been developed.
For example, there are techniques of visually detecting forgery based on external appearance. Specifically, there are techniques of incorporating fluorescent substances in printed matter; a technique of printing with magnetic ink to permit visual detection of the change in density of the ink by magnetic effects (Japanese Unexamined Patent Publication (KOKAI) Heisei No. 5-177919); the technique of printing with ink comprising photochromic light-sensitive pigments (Japanese Unexamined Patent Publication (KOKAI) Showa No. 60-79992); techniques of printing with ink having specific reflection spectroscopic characteristics or two or more inks having differences in reflectance exceeding a prescribed value; printed matter exhibiting change in color when viewed from a certain angle (Japanese Unexamined Patent Publication (KOKAI) Heisei No. 5-177919); printed matter imparted with a watermark (latent image) (Japanese Examined Patent Publication (KOKOKU) Heisei No. 4-18078, Japanese Unexamined Utility Model Publication (JIKKAI) No. Showa 58-168457); and the like.
Further, printed matter that has been finely processed to render reading of the text and images on a copied paper difficult, and warning marks that appear on a copied paper have been developed (Japanese Unexamined Utility Model Publication (JIKKAI) No. Showa 59-64271).
There are also materials that are printed with special magnetic ink so that an error occurs when a copy is placed on a discriminating device; printed materials that are printed so that the density of printed halftones on copies differs from that of the original (authentic note) (Japanese Examined Patent Publication (KOKOKU) Showa No. 56-19273 and Heisei No. 2-51742); and materials on which are printed characters that cannot be discerned by the naked eye but on which hidden characters can be read with a discriminating device (Japanese Unexamined Patent Publication (KOKAI) Showa No. 62-130874).
Although such a variety of forgery-preventing strategies has been developed, most of the originals can be duplicated by graphic platemaking, and these forgery-preventing strategies cannot be considered complete. Further, many items such as authentic notes develop wrinkles during use, and are then rejected by the discriminating device as “Unusable”.
In consideration of these problems of prior art, the present invention has for its object to provide a forgery-preventing film that can be readily distinguished from copies, tends not to wrinkle, and affords good print adhesion.